1. Field of the Invention
The invention relates to a process for controlling of the positioning of workpiece and tool with a robot in a production machine.
2. Related Art of the Invention
In DE 101 25 445 A1 a process for the control of the motion of a robot is disclosed in which faster cycle times are achieved by limiting the maximum axis speed only for the conditions where in fact a kinetic energy would result which is too high. Thus, a workpiece carried by a robot grip can be moved faster into its processing position.
DE 102 29 293 A1 discloses a process for the determination of the orientation of a robot axis with respect to a robot coordinate system in which the expenditure of time is reduced by a coordinate measurement device which is located outside of the robot system and which acquires and processes the coordinates of reference points at two different moving positions of the robot.
In a production machine, especially a milling machine according to DE 199 30 287 A1, the mobility of the whole machine is optimized by holding a tool in two opposing articulating arms and positioning the tool is under restricted freedom of movement in real time with respect to a workpiece. While moving the tool between the articulating arms the forces are carried with a favorable angle predominantly by the arm which is closer to the tool such that for the precision and load unfavorable fully extracted positions like in simpler robot joint constructions are counteracted by the opposing articulating arms. Since the machine has a restricted freedom of movement it is of limited use for three-dimensional processing.
In a system according to EP 1321225 A2 the working axis are distributed between the moving direction of the tool spindle and the moving direction of the tool, i.e. one axis which otherwise would be assigned to the spindle is eliminated. The tool spindle moves according to the movement of the workpiece to reduce the constructive complexity for the movability of the tool spindle.
For the known machining processes in which a tool or a workpiece is positioned by a robot the positioning takes longer than the actual processing or machining. In robot supported joining methods like spot welding, clinching or punch riveting, the positioning time is typically between 1 s and 1.5 s whereas the joining process itself is finished after 0.2 s to 0.8 s.